Stihl MS290 Chainsaw Parts Manual

The Stihl MS290 Farm Boss is a professional-grade chainsaw featuring a powerful 56.5cc engine, robust construction, and a range of safety and performance features. This parts manual provides detailed diagrams, part numbers, and ordering information for maintenance, repair, and replacement of components. Below are key sections covering identification, major assemblies, engine components, cutting equipment, and ordering guidelines.

1. Identification & Specifications 2. Major Assemblies & Diagrams 3. Engine Components 4. Fuel & Ignition System 5. Cutting Equipment & Bar 6. Crankcase & Clutch Assembly 7. Starter & Recoil System 8. Housing & Handle Components 9. Safety & Maintenance Parts 10. Ordering Information 11. Troubleshooting & Exploded Views

Identification & Specifications

Key identifiers: Model MS290, also known as Farm Boss. Engine displacement: 56.5 cc. Power output: 3.4 bhp. Weight (without cutting equipment): Approximately 13.2 lbs. Fuel tank capacity: 16.9 fl oz. Oil tank capacity: 8.5 fl oz. Guide bar lengths: 16", 18", 20". Chain pitch: 3/8" or .325".

FeatureDescription
Engine Type2-stroke, single cylinder, air-cooled
Ignition SystemElectronic, capacitor discharge (CDI)
CarburetorStihl Zama C1Q-S series
Fuel/Oil Mix50:1 (Stihl HP Ultra or equivalent)
Chain BrakeInertia-activated, manual release
Anti-VibrationSpring-mounted handle system
StarterRewind starter with decompression valve
Bar & ChainRollomatic E bar, Stihl Oilomatic chain
Spark PlugNGK BPMR7A (gap 0.020")
Serial Number LocationOn crankcase, near rear handle

Major Assemblies & Diagrams

Exploded view diagrams show component relationships and part numbers.

  1. Cylinder & Piston Assembly: Includes cylinder, piston, rings, wrist pin, circlips.
  2. Crankcase Assembly: Crankcase halves, crankshaft, bearings, seals.
  3. Fuel System Assembly: Fuel tank, cap, filter, lines, carburetor.
  4. Ignition Assembly: Flywheel, ignition module, spark plug wire, stop switch.
  5. Clutch & Sprocket Assembly: Clutch drum, centrifugal clutch, rim sprocket.

WARNING! Always disconnect spark plug before disassembly. Use genuine Stihl parts for safety and performance.

Engine Components

Detailed parts list for engine rebuild and maintenance.

  1. Cylinder: Part # 1128 020 1205 (with decompression valve port).
  2. Piston: Part # 1128 030 2001 (56.5cc, includes rings).
  3. Crankshaft: Part # 1128 030 4201.
  4. Connecting Rod: Part # 1128 030 2103.
  5. Crankcase Set: Part # 1128 020 0603 (includes seals and gaskets).
  6. Bearings: Main bearings (6202 C3 and 6203 C3).
  7. Seals: Crankshaft seals (15x28x7 mm).

CAUTION! Torque specifications must be followed. Cylinder head bolts: 14 Nm (10 ft-lb).

Fuel & Ignition System

Cutting Equipment & Bar

Guide Bar: Stihl Rollomatic E. Chain: Stihl Oilomatic. Sprocket: Rim or spur type.

Bar Parts: Bar nose sprocket (Part # 0000 350 7501), bar rails, grease hole plug. Chain Parts: Drive links, cutters, tie straps, rivets. Clutch Drum: Part # 1128 640 2001. Rim Sprocket: Part # 0000 642 2003 (3/8" pitch).

Chain Tensioner: Part # 1128 160 2600 (includes adjusting screw and pin). Bar Mount Studs: Part # 1128 647 3400. Chain Catcher: Part # 1128 650 7701.

Crankcase & Clutch Assembly

Clutch: Centrifugal, engages at ~2800 RPM. Parts include clutch shoes, springs, drum.

  1. Remove clutch: Use clutch holding tool and counterclockwise rotation.
  2. Clutch Shoes: Part # 1128 160 2100 (set of 3).
  3. Clutch Springs: Part # 1128 160 2201.
  4. Needle Bearing: Part # 1128 160 2501 (clutch drum bearing).
  5. Oil Pump: Part # 1128 647 0800 (automatic and manual).
  6. Oil Lines: Part # 0000 350 0920 (delivery) and 0000 350 0910 (return).

Tip: Clean oil passages regularly to prevent bar and chain damage.

Starter & Recoil System

Rewind starter with decompression valve assist.

  1. Starter Housing: Part # 1128 080 0601.
  2. Starter Rope: Part # 0000 350 2100 (1.8m, 3mm diameter).
  3. Starter Pulley: Part # 1128 080 0800.
  4. Spring: Part # 0000 350 4100 (recoil spring).
  5. Decompression Valve: Part # 1128 141 0600.
  6. Starter Handle: Part # 0000 350 2905.

WARNING! Wear gloves when handling recoil spring; it is under high tension.

Housing & Handle Components

Anti-vibration system: Springs and dampers isolate handle from engine.

Safety & Maintenance Parts

Chain Brake Assembly: Band (Part # 1128 650 7501), lever, spring. Throttle Lockout: Part # 1128 918 0500. Muffler: Part # 1128 140 3601 (with spark arrestor screen). Air Filter: Part # 0000 350 2601 (felt pre-filter available).

CAUTION! Replace chain brake components if damaged. Never operate with defective safety features.

Ordering Information

Use genuine Stihl parts for warranty and safety. Provide model number (MS290) and serial number when ordering. Parts available through authorized Stihl dealers. Exploded views and part numbers in this manual are for reference; verify with dealer for latest revisions. Copyright © 2025 Stihl Incorporated. Stihl and MS290 are registered trademarks. For support, visit www.stihlusa.com or contact 1-800-467-8445.

Troubleshooting & Exploded Views

SymptomPossible CauseParts to Check/Replace
Engine won't startFuel, spark, compressionSpark plug, fuel filter, carburetor kit, ignition module.
Loss of powerAir filter, muffler, pistonAir filter, muffler screen, piston & cylinder kit.
Chain won't oilOil pump, lines, bar holeOil pump, oil lines, check bar oil passage.
Clutch slippingWorn shoes/springsClutch shoe & spring kit.
Vibration excessiveAV mounts, crank balanceAnti-vibration mounts, check crankshaft and bearings.
Starter rope won't retractBroken spring, jammed pulleyRecoil spring, starter pulley, clean housing.

Exploded Views: Refer to detailed diagrams for each assembly (Cylinder Group, Fuel System, Clutch, etc.) showing part numbers and assembly order.

Service: 1-800-467-8445; www.stihlusa.com

Stihl MS290 Chainsaw Parts Manual © - All Rights Reserved 2025